Magnetic head-based system have been widely accepted in the computer industry as a cost-effective form of data storage. In a magnetic tape drive system, a magnetic tape containing a multiplicity of laterally positioned data tracks that extend along the length of the tape is drawn across a magnetic read/write transducer, referred to as a magnetic tape head. The magnetic tape heads can record and read data along the length of the magnetic tape surface as relative movement occurs between the heads and the tape.
In magnetic recording systems, the mechanical interaction of the magnetic head and the recording medium is an important factor determining the performance and reliability of the system. Ideally, the head is in contact or near contact with the moving recording medium to optimize read/write processes. The contact at the head/medium interface results in wear which is a major concern affecting performance and lifetime of both head and medium.
Tape heads may have a protective coating on them to protect the read/write elements from wear, corrosion, shorting, poor handling, etc. During the head manufacturing phase, it is preferable, for reliability purposes, to determine whether a head has been properly coated. Similarly, during a head failure analysis or diagnostic analysis, it may also be desirable to determine whether a protective coating remains on the head, and perhaps, if so, the extent that the coating remains.
It would therefore be desirable to have a system or method of detecting whether a head has a protective coating on it. However, because most coatings are only tens of Angstroms thick, detecting such coatings is very difficult. For instance, optical interferometry is unable to resolve the surface of the coating and the underlying head surface. Auger materials analysis is unable to discern whether the top layer of carbon is coming from the environment or the protective coating. Other methods such as nono-indentation, focused ion beam (FIB) analysis, etc., are destructive and not always conclusive.